Field of the Invention
The present invention relates to an optical fiber cable.
Description of the Related Art
With an optical communication system using an optical fiber arranged in a transmission line, it is desirable to transmit information in high volume. In general, since an optical wavelength band used for an optical communication system is limited to C band: 1530 to 1565 nm and L band: 1565 to 1610 nm, to transmit information in high volume, it is desirable that spectral efficiency (SE) [b/s/Hz] expressing a transmission capacity per frequency is high. Also, an optical fiber cable which includes and integrally covers a plurality of optical fibers is arranged in, for example, a conduit line placed underground. Since the space in the conduit line is limited, it is desirable to transmit information in higher volume with an optical fiber cable having a smaller sectional area. Spectral efficiency per unit sectional area of an optical fiber cable is expressed as a spatial spectral efficiency (SSE) [b/s/Hz/mm2].
Japanese Unexamined Patent Application Publication No. 2014-067020 discloses an optical fiber that improves an optical signal to noise ratio (OSNR) while taking account of high-density packing in an optical cable. Also, International Publication No. 2013/129234 discloses an optical fiber that increases SE per unit sectional area of an optical fiber. With the optical fiber described in Japanese Unexamined Patent Application Publication No. 2014-067020, an effective area Aeff is limited to 100 μm2 or smaller. Also, SSE of the optical fiber cable is not considered. The optical fiber described in international Publication No. 2013/129234 is a multi-core optical fiber, but is not a single core fiber. Also, an optical fiber cable is not considered.